I bought a TV dongle today (Telekom Magenta TV Stick) that runs Android TV and so far I'm loving it.

It plugs into my TV (Hisense 43AE7010F) via HDMI.
I'm using an optical audio cable that goes from the TV to my SMSL 793II headphone DAC/AMP for when I want to use headphones instead of the TV speakers.

However I can't adjust the volume for that optical output through my TV and the Android volume selector doesn't go low enough for comfortable listening even if I turn the DAC/AMP as far down as I can without causing channel imbalance (about 1/5 volume).

I have a similar problem on PC but for that I simply use the program 'Equalizer APO' to apply a -20 dB volume reduction for the output.

Is there a similar app available for Android TV that allows me to do this?

Thanks